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el sid



Member Since: 06 Sep 2025
Location: devon
Posts: 21
England 1996 Defender 90 300 Tdi CSW Barolo Black
Rev gauge.
Has any one fitted a cheap rev counter to a 300TDI,if so which one?i know about the vdo ones, but if a cheap one works ,why not?(yep buy twice,i know Laughing )
Post #1075047 8th Sep 2025 6:21pm
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julian



Member Since: 17 Feb 2017
Location: Devon
Posts: 204
United Kingdom 1994 Defender 110 300 Tdi CSW Alpine White
I've got a cheap 52mm eBay one on mine.

Runs off the w terminal. Looks in keeping with the other gauges (white led, not green though)

You have to calibrate them using a tacho, or just roughly by experience.

They're about £25 ish, iirc.
Post #1075049 8th Sep 2025 7:08pm
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el sid



Member Since: 06 Sep 2025
Location: devon
Posts: 21
England 1996 Defender 90 300 Tdi CSW Barolo Black
Ive seen some where that you set them at tickover revs ie 750 to 800,is that what you mean?
Post #1075053 8th Sep 2025 7:42pm
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julian



Member Since: 17 Feb 2017
Location: Devon
Posts: 204
United Kingdom 1994 Defender 110 300 Tdi CSW Alpine White
Out of the box, they "know" that "zero" pulses from the w terminal is 0rpm.

But, say you rev to 1000rpm - some setups will put out more pulses than others at that engine speed.

So you need to take it to a know rpm (doesn't really matter what that is, so long as you know it) and then dial the gauge to that rpm.

Then it will know that zero pulses means 0rpm and whatever it gets when you told it 1000rpm is 1000rpm, and, from that, it can, more or less, scale all the other values.
Post #1075054 8th Sep 2025 7:49pm
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Hazza



Member Since: 10 Jan 2011
Location: North Yorkshire / Leeds
Posts: 244
United Kingdom 1990 Defender 110 Td5 HT Bronze Green
Most of the cheap ones can be prized apart, then you can put a dab of green glass paint on the LEDs to change the colour. Someone more skilled could probably change the LEDs to green! 1990 Defender 110 200TDI Camper - now converted to Td5 power
Post #1075060 8th Sep 2025 9:06pm
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el sid



Member Since: 06 Sep 2025
Location: devon
Posts: 21
England 1996 Defender 90 300 Tdi CSW Barolo Black
julian wrote:
Out of the box, they "know" that "zero" pulses from the w terminal is 0rpm.

But, say you rev to 1000rpm - some setups will put out more pulses than others at that engine speed.

So you need to take it to a know rpm (doesn't really matter what that is, so long as you know it) and then dial the gauge to that rpm.

Then it will know that zero pulses means 0rpm and whatever it gets when you told it 1000rpm is 1000rpm, and, from that, it can, more or less, scale all the other values.
THANKS, THATS MADE IT MORE CLEAR ON HOW THEY WORK.
Post #1075068 8th Sep 2025 10:05pm
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el sid



Member Since: 06 Sep 2025
Location: devon
Posts: 21
England 1996 Defender 90 300 Tdi CSW Barolo Black
Just fitted my £17.89 chinese tachometer,mainly to see how many revs the Romer overdrive unit drops the revs.(haven't tried it on the road yet)It never came with instructions on how to calibrate,and if they do they are in Chinese!.mine was reading 1100 on tickover,ive set it to 750/800. On U TUBE there is a guy that shows how to do it touching the white wire to earth.Hope this helps if you get one.ps some are adjusted by a screw,but not this one.
Post #1076625 1st Oct 2025 12:12pm
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el sid



Member Since: 06 Sep 2025
Location: devon
Posts: 21
England 1996 Defender 90 300 Tdi CSW Barolo Black
The Romer overdrive drops the revs by 28%so about 1100 revs at 4000,560 at 2000.70mph nice and quiet (once i change the straight through exhaust) Embarassed
Post #1077421 13th Oct 2025 8:24pm
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